Biology subjects

Willink, B.

Publications and source records attributed to Willink, B..

6 recordsLinked to original sources

bioRxiv2025

Ecology and sexual conflict drive the macroevolutionary dynamics of female-limited colour polymorphisms

Sexual conflict over mating has been documented in many species, both in the field and in experimental studies. In pond damselflies (family Coenagrionidae), sexual conflict maintains female-limited colour poly-morphisms, with one female morph typically being a male mimic. However, it is not known whether sexual conflict can also explain the evolutionary origin of novel female morphs, and if so, what ecological factors play a role in this macroevolutionary transition, by modulating the strength of the conflict. Furthermore, the effects of sexual conflict on phylogenetic diversification remain controversial, with studies arguing that the evolution of alternative reproductive morphs, such as female-limited colour morphs, could either hinder or accelerate speciation. Here, we use phylogenetic comparative methods to show that female colour polymorphisms are more likely to evolve when population densities at breeding sites are high, and that these demographic conditions are more common at high latitudes and in open landscapes. We show that female-limited polymorphisms typically evolve from sexually dimorphic ancestors through the addition of a male-like female morph, consistent with the hypothesis of selection for male mimicry. Female polymorphic and sexually dimorphic lineages diversify at a higher rate than sexually monomorphic lineages, suggesting a broad diversity-promoting role of inter-sexual interactions based on visual signals. We conclude that female colour polymorphisms evolve in a predictable fashion, and are likely driven by ecological conditions that increase the rate of pre-mating interactions and thus the intensity of sexual conflict.

evolutionary biology↗

bioRxiv2024

Eyespots originated multiple times independently across the Lepidoptera

Eyespot colour patterns are an effective defence against predators and are found in many animal lineages. In nymphalid butterflies, eyespots have a single evolutionary origin close to the base of this clade, but eyespots are also present in many other lepidopteran lineages and may have multiple independent origins. Here we use phylogenetic comparative methods to investigate the evolution of eyespots across a multi-superfamily phylogeny of Lepidoptera, and to pinpoint lineages in which eyespots likely originated independently. We find a total of 32 separate origins of Discal eyespots (in the discal wing region) and 21 separate origins of Marginal eyespots (in the marginal wing region). In two instances, eyespots were preserved in most extant representatives of a subsequent species radiation. In one such instance, in the Nymphalidae, ancestral state reconstructions suggest that an ancestor with Marginal eyespots predated the origin of one or more lineages with Discal eyespots, while in the Saturniidae we observed the opposite. We conclude that eyespots do not appear to be homologous across the Lepidoptera. Our phylogenetic inference provides a roadmap for future developmental and functional studies that can address whether Discal and Marginal eyespots share the same gene-regulatory network. This study, therefore, has implications for our understanding of the evolution of serial homologues and of convergent evolution of visual signals in insects.

developmental biology↗

bioRxiv2023

The genomics and evolution of inter-sexual mimicry and female-limited polymorphisms in damselflies

Sex-limited morphs can provide profound insights into the evolution and genomic architecture of complex phenotypes. Inter-sexual mimicry is one particular type of sex-limited polymorphism in which a novel morph resembles the opposite sex. While inter-sexual mimics are known in both sexes and a diverse range of animals, their evolutionary origin is poorly understood. Here, we investigated the genomic basis of female-limited morphs and male mimicry in the Common Bluetail damselfly. Differential gene expression between morphs has been documented in damselflies, but no causal locus has been previously identified. We found that male-mimicry originated in an ancestrally sexually-dimorphic lineage in association with multiple structural changes, probably driven by transposable element activity. These changes resulted in [~]900 kb of novel genomic content that is partly shared by male mimics in a close relative, indicating that male mimicry is a trans-species polymorphism. More recently, a third morph originated following the translocation of part of the male-mimicry sequence into a genomic position [~]3.5 mb apart. We provide evidence of balancing selection maintaining male-mimicry, in line with previous field population studies. Our results underscore how structural variants affecting a handful of potentially regulatory genes and morph-specific genes, can give rise to novel and complex phenotypic polymorphisms.

evolutionary biology↗

bioRxiv2022

Tropical origin, global diversification and dispersal in the pond damselflies (Coenagrionoidea) revealed by a new molecular phylogeny

The processes responsible for the formation of Earths most conspicuous diversity pattern, the latitudinal diversity gradient (LDG), remain unexplored for many clades in the Tree of Life. Here, we present a densely-sampled and dated molecular phylogeny for the most speciose clade of damselflies worldwide (Odonata: Coenagrionoidea), and investigate the role of time, macroevolutionary processes and biome-shift dynamics in shaping the LDG in this ancient insect superfamily. We used process-based biogeographic models to jointly infer ancestral ranges and speciation times, and to characterise within-biome dispersal and biome-shift dynamics across the cosmopolitan distribution of Coenagrionoidea. We also investigated temporal and biome-dependent variation in diversification rates. Our results uncover a tropical origin of pond damselflies and featherlegs [~] 105 Ma, while highligthing uncertainty of ancestral ranges within the tropics in deep time. Even though diversification rates have declined since the origin of this clade, global climate change and biome-shifts have slowly increased diversity in warm- and cold-temperate areas, where lineage turnover rates have been relatively higher. This study underscores the importance of biogeographic origin and time to diversify as important drivers of the LDG in pond damselflies and their relatives, while diversification dynamics have instead resulted in the formation of ephemeral species in temperate regions. Biome-shifts, although limited by tropical niche conservatism, have been the main factor reducing the steepness of the LDG in the last 30 Myr. With ongoing climate change and increasing northward range expansions of many damselfly taxa, the LDG may become less pronounced. Our results support recent calls to unify biogeographic and macroevolutionary approaches to increase our understanding of how latitudinal diversity gradients are formed and why they vary across time and among taxa.

evolutionary biology↗

bioRxiv2020

A molecular phylogeny of forktail damselflies (genus Ischnura) reveals a dynamic macroevolutionary history of female colour polymorphisms

Colour polymorphisms are popular study systems among biologists interested in evolutionary dynamics, genomics, sexual selection and sexual conflict. In many damselfly groups, such as in the globally distributed genus Ischnura (forktails), sex-limited female colour polymorphisms occur in multiple species. Female-polymorphic species contain two or three female morphs, one of which phenotypically matches the male (androchrome or male mimic) and the other(s) which are phenotypically distinct from the male (heterochrome). These female colour polymorphisms are thought to be maintained by frequency-dependent sexual conflict, but their macroevolutionary histories are unknown, due to the lack of a robust molecular phylogeny. Here, we present the first time-calibrated phylogeny of Ischnura, using a multispecies coalescent approach (StarBEAST2) and incorporating both molecular and fossil data for 41 extant species (55% of the genus). We estimate the age of Ischnura to be between 13.8 and 23.4 millions of years, i.e. Miocene. We infer the ancestral state of this genus as female monomorphism with heterochrome females, with multiple gains and losses of female polymorphisms, evidence of trans-species female polymorphisms and a significant positive relationship between female polymorphism incidence and current geographic range size. Our study provides a robust phylogenetic framework for future research on the dynamic macroevolutionary history of this clade with its extraordinary diversity of sex-limited female polymorphisms.

evolutionary biology↗

bioRxiv2019

Gene expression changes during female reproductive development in a colour polymorphic insect

Pleiotropy (multiple phenotypic effects of single genes) and epistasis (gene interaction) have key roles in the development of complex phenotypes, especially in polymorphic taxa. The development of discrete and heritable phenotypic polymorphisms often emerges from major-effect genes that interact with other loci and have pleiotropic effects on multiple traits. We quantified gene expression changes during ontogenetic colour development in a polymorphic insect (damselfly: Ischnura elegans), with three heritable female morphs, one being a male mimic. This female colour polymorphism is maintained by male mating harassment and sexual conflict. Using transcriptome sequencing and de novo assembly, we demonstrate that all three morphs downregulate gene expression during early colour development. The morphs become increasingly differentiated during sexual maturation and when developing adult colouration. These different ontogenetic trajectories arise because the male-mimic shows accelerated (heterochronic) development, compared to the other female morphs. Many loci with regulatory functions in reproductive development are differentially regulated in the male-mimic, including upstream and downstream regulators of ecdysone signalling and transcription factors potentially influencing sexual differentiation. Our results suggest that long-term sexual conflict does not only maintain this polymorphism, but has also modulated the evolution of gene expression profiles during colour development of these sympatric female morphs.

evolutionary biology↗